Surgically resected subretinal proliferative tissue (SRP) in proliferative vitreoretinopathy was examined by morphological and immunohistochemical methods. Membranous and strand-like SRPs were observed. Membranous SRP (4 cases) consisted of retinal pigment epithelial cells (RPEs) and a thin layer of extracellular materials. Strand-like SRP (14 cases) had a core, in which the proliferated cells were embedded among extracellular materials. RPEs and glial cells were found on the surface of the core. Immunohistochemical investigation revealed that the predominant cell components of the strand-like SRPs were RPEs and Müller cells, whereas membranous SRPs were composed mainly of RPEs. It was found that the majority of membranous and strand-like SRPs contained types I, III and IV collagens and fibronectin in the extracellular space. Based on the results of this study, a hypothetical process for the formation of SRP tissues was proposed.